The current emphasis on graphical user interfaces (GUIs), justified as it may be, has lead to a regrettable stagnation in the development of command language user interfaces (CLUIs) for operating systems and applications such as image processing, data analysis, database access or wide-area information retrieval. In a case study involving the implementation of interfaces to archie, FTP, WAIS and an SQL-based database management system, the virtues of functional, collection-oriented CLUIs are demonstrated. The prototype implementation allows e.g. easy chaining of base modules and thus functional layering through composition. It permits the integration of services of quite different origins within a flexible and powerful programming environment. A list of desiderata for future CLUIs is distilled from the experience.